This invention relates generally to inflatable passive restraint systems such as used in motor vehicles to restrain the movement of a seated occupant during a collision and, more particularly, to the assembly of such an inflatable passive restraint system.
Safety restraint systems which self-actuate from an undeployed to a deployed state without the need for intervention by the operator, i.e., "passive restraint systems", and particularly those restraint systems incorporating inflatable bags or cushions, as well as the use of such systems in motor vehicles have gained general appreciation.
It is well known to protect a vehicle occupant using a cushion or bag that is inflated with gas, e.g., an "airbag", when the vehicle encounters sudden deceleration, such as in the event of a collision. During deployment, the rapidly evolving gas with which the bag is typically filled is an inert gas, e.g., nitrogen. In such systems, the airbag is normally housed in an uninflated and folded condition to minimize space requirements. In an emergency, gas is discharged from an inflator to rapidly inflate the airbag. The airbag, upon inflation, serves to restrain the movement of the vehicle occupant as the collision proceeds. In general, such airbags are commonly designed to be inflated in no more than a few milliseconds.
Vehicular inflatable restraint systems generally include multiple crash sensors generally positioned about or mounted to the frame and/or body of the subject vehicle and serve to sense sudden decelerations of the vehicle. In turn, the sensor sends a signal to an airbag module or assembly strategically positioned within the riding compartment of the vehicle to actuate deployment of the airbag. In general, an airbag provided for the protection of a vehicle driver, i.e., a driver side airbag, is mounted in a storage compartment located along the steering column of the vehicle.
Typical inflatable cushion restraint systems make use of an airbag module which generally includes an outer reaction housing or canister, commonly referred to as a "reaction can" or, more briefly, as a "can". The reaction canister generally serves to support or contain other components of the airbag module system, including what is referred to as a "airbag inflator" or, more briefly, as an "inflator", or, alternatively, as a "generator". The inflator, upon actuation, acts to provide the gas to inflate the airbag/cushion.
The types of inflators typically used in such systems include pyrotechnic and hybrid inflators. Pyrotechnic inflators generally contain a gas generating material which, upon activation, generates gas used to inflate the airbag/cushion. In general, the inflation gas produced by a pyrotechnic inflator is emitted from openings or emission ports along the length of the inflator. In contrast, hybrid inflators in addition to a body of ignitable pyrotechnic material generally contain, as the primary inflation gas, a compressed gas which upon proper actuation is expelled from the inflator. As a consequence of the physics associated with the storage of compressed gases, the container used to store this compressed gas typically has a cylindrical shape.
Furthermore, the discharge of gas from such a cylindrically shaped gas storage container typically occurs by way of openings or emission ports at only one end of the cylindrical container. To attain proper bag deployment, however, it is generally desired that the emission of gas into the airbag/cushion from such a storage container be done in a fairly uniform manner. With typical airbag/inflator assemblies, such uniform emission is generally attained by having a relatively even emission of gas into the deploying bag along the length of the gas inlet opening of the bag connected, directly or indirectly, to the inflator. In this way the bag is properly uniformly deployed and the risk of the bag deploying in a skewed manner due to the discharge of gas from only one end of the storage container is avoided.
The reaction housing is typically in the form of an open-mouthed container, formed by one or more body parts with an end plate fastened at each opposed end of the container. Usually, the airbag/cushion, in an uninflated and folded condition, is also placed into such an open-mouth reaction canister housing. In practice, the component parts of such prior art inflatable restraining devices, particularly the component parts of the reaction canister, e.g., the body part or parts and two end plates, one at each opposite end and especially reaction canister assemblies utilizing part or parts formed by extrusion fabrication, are commonly joined and held together through the use of a multiple number of selected fasteners such as screws, rivets or bolts.
For example, a selected fastener is typically passed through fastener holes which have been preformed in the respective parts to be fastened together. The production of assemblies that utilize multiple fasteners typically require additional machinery and associated personnel. For example, facilities for the production of such assemblies requiring multiple fasteners commonly include fixture devices to effect proper fastener hole alignment for insertion of a fastener and some form of a driver device in order to drive the fastener into the fastener hole. Such additional production steps slow the assembly process and increase the costs associated with such assemblies.
Furthermore, each fastener is an entity in and of itself with each such fastener needing to be tightened to a specific torque, thereby complicating the assembly process. For example in order to better ensure safety in and proper functioning of airbag module assemblies, the component parts of the assembly, including fasteners, and the particulars of each such use of a component part is desirably recorded and tracked. Such recording and tracking operations, however, are undesirably complicated as the number of component parts of a particular assembly is increased. In view thereof, airbag module assemblies are generally preferably designed to minimize the number of component parts used therein.
Thus, a relatively simple, low cost reaction canister assembly which: 1) reduces and/or minimizes the number of component parts incorporated therein and 2) reduces and/or minimizes the use of fasteners such as rivets, bolts, and screws to effect attachment and the problems associated with the use of such fasteners, such as those identified herein, is desired.